In general, most of integrated circuits (IC) can provide different operation modes to match the user's requirement according to the configuration setting. And the operation mode of an IC is usually configured at the time of IC being turned on or being reset, so as to ensure the IC can be operated at the correct mode. Normally, the configuration setting method of the IC is determined by providing a supply voltage or ground voltage to a specific pin of the IC. Thus, if the operation mode requirements of the IC are increased, the pin counts of the IC will also need to be increased. However, once the more pin counts the IC has, the relative cost of the IC will correspondingly increased. Therefore, how to reduce the pin counts required by the configuration setting of an IC is still a design target for every engineer. The related techniques and research can refer to U.S. Pat. No. 6,831,479 and R.O.C. Patent publication No. 200633381.